This invention relates to a two way flow control device and, more particularly, to a two way flow control device for use in a heat pump refrigerant circuit.
Normally in a conventional refrigerant circuit an expansion means is provided between the condenser and evaporator in order to meter the flow of refrigerant from the condenser to the evaporator so as to provide a pressure drop for refrigeration effect. The expansion means is ordinarily a capillary tube which relies upon a fixed geometry to achieve refrigerant throttling or an expansion valve has been used in place of the capillary tube.
To convert an ordinary refrigerant system to a heat pump, it is necessary to thermodynamically reverse the flow of refrigerant. The direction of refrigerant flow through the circuit is reversed by changing the connection between the suction and discharge side of the compressor with a four way valve or a reversing valve. The cooling condensor now functions as an evaporator while the cooling evaporator serves as a heating condenser. Reversible refrigerant cycles or heat pump circuits have heretofore generally utilized either parallel capillary tubes with check valves or a double expansion valve and bypass system positioned in the fluid line connecting the two heat exchangers to accomplish throttling in either direction. The Duell et al. U.S. Pat. No. 3,992,898, for example, shows a heat pump system which incorporates a pair of metering devices mounted in opposed relationship in a supply line carrying refrigerant between the two heat exchangers in a heat pump system. Each metering device includes a free-floating piston having an orifice therein slidably mounted in the body of the metering device. There is sometimes instability of operation because the orifice is in the movable piston, which does not always seal with its seat and therefore there may be leakage around the orifice in the movable piston. Turbulence of the refrigerant may cause the movable piston to undesirably back off its valve seat during operation.
An object of the present invention is to provide an improved two way flow control device for metering the refrigerant properly during both the heating cycle and the cooling cycle of a heat pump.
Another object of the present invention is to provide a relatively inexpensive two way flow control device specially suited for use in a heat pump refrigerant circuit, that will accurately throttle the flow of refrigerant in the cooling mode of operation of the heat pump.
Yet another object of the present invention is to provide a two way flow control device for a heat pump refrigerant circuit that has fixed orifice means therein and a thin wafer type valve member for sealing effectively the bypass of refrigerant around the orifice means, which provide for stability in operation.
Other objects and advantages of the present invention will be made more apparent hereinafter.